1. Field of the Invention
The present invention relates generally to an optical connector, and more particularly to an optical connector as an optical plug wherein an optical fiber cable is led out in a direction different from an axial direction of a ferrule connected with the optical fiber cable.
2. Description of the Related Art
An optical connector is used to connect an optical fiber cable with a transmitter, a receiver, or another optical fiber cable constituting a multiplex transmission circuit, for example, of a vehicle such as motor vehicle.
Because the optical fiber cable is weak in extreme bending and distortion, the optical fiber cable is usually led out of the optical connector straight. In a circumstance, like in a vehicle, that various electric equipment and wiring harnesses are thickly arranged, however, the optical fiber cable is often led out of the optical connector, while being curved in a minimum bending radius.
An optical connector disclosed in Japanese Patent Application Laid-open No. 10-78534 is known as an optical connector with a curved optical fiber cable. And, another optical connector 1 shown in FIG. 10 is also used.
Hereinafter, the above optical connector 1 will be described, referring to FIG. 10. The optical connector 1 consists of a receptacle (not illustrated) and an optical plug 2 to be coupled with the receptacle. The optical plug 2 has ferrule assemblies 3, a plug housing 4, and a spring cap 5.
The ferrule assembly 3 is formed by connecting a ferrule 8 on the end of an optical fiber cable 7 on which a compression spring 6 is arranged. One end of the compression spring 6 abuts against the ferrule 8.
The plug housing 4 couples with a coupling portion (not illustrated) of the receptacle and has longitudinal accommodating chambers 9 to accommodate the respective ferrule assemblies 3. And, a claw-like engaging projection 10 is protrusively-provided on each sidewall of the plug housing 4. (One engaging projection 10 is illustrated.)
The spring cap 5 consists of a lower spring cap 11 and an upper spring cap 12, which lower spring cap 11 engages the rear of the plug housing 4.
The lower spring cap 11 has an engaging portion 13 to engage the plug housing 4 and a leading-out direction restricting portion 14 to restrict the direction of the optical fiber cables. The engaging portion 13 is provided with four-sided holes 15 to engage the engaging projections 10 and fiber leading-out portions 16 against which the other ends of the respective compression springs 6 abut and through which the optical fiber cables 7 pass.
The leading-out direction restricting portion 14 curves the optical fiber cables 7 by about 90xc2x0 for leading them in a lateral direction. The curved optical fiber cables 7 are led outside out of an opening portion 17 provided on the leading-out direction restricting portion 14. A sidewall of the leading-out direction restricting portion 14, at a side of a smaller radius of curvature, is provided with a supporting surface 18 curving in a circular-arc. And, another sidewall of the leading-out direction restricting portion 14, at a side of a large radius of curvature, is provided with engaging projections 19 and ribs 20 to engage the upper spring cap 12 and is formed to make the optical fiber cables 7 curve.
The upper spring cap 12 is formed to cover the leading-out direction restricting portion 14 of the lower spring cap 11. And, a sidewall 21 of the upper spring cap 12 is provided with four-sided holes 22 to engage the above engaging projections 19 and guide grooves 23 to receive the above ribs 20.
With respect to the above conventional optical connector 1, however, because the optical fiber cable 7 connected to the ferrule 8 is thick, the rigidity of the optical fiber cable 7 is big, thereby bringing about poor work efficiency and making the optical connector large. Further, because the compression spring 6 is pushed by the optical fiber cable 7, the action of the compression spring 6 would be hindered, thereby making a connecting force bigger.
More specifically, because the optical fiber cable 7 generally has a core fiber portion (not illustrated), a primary sheathing (not illustrated) covering the core fiber portion, and a secondary sheathing 7a covering the primary sheathing, the optical fiber cable 7 is fairly thick and has a fairly big rigidity. And, a work to accommodate the thick optical fiber cable 7 with a minimum radius of curvature in the spring cap 5, as shown in FIG. 11, causes poor work efficiency.
Also, because the thick optical fiber cable 7 needs the larger opening portion 17, an end width d of the spring cap 5 has to be larger, thereby making the optical plug larger.
Further, as shown in FIG. 1, when the optical fiber cable 7 is curved with a minimum radius of curvature, the compression spring 6 is pushed by the optical fiber cable 7 toward an inside wall of the plug housing 4, the action of the compression spring 6 would be hindered, thereby making a connecting force with a receptacle (not illustrated) bigger.
In view of the foregoing, an object of the present invention is to provide an optical connector wherein the work efficiency is enhanced, a downsizing is achieved, and a connecting force is smaller.
In order to achieve the above-described object, as a first aspect of the present invention, an optical connector as an optical plug comprises: an optical fiber cable; a ferrule connected to an end of the optical fiber cable and constructing a ferrule assembly along with the optical fiber cable; a spring arranged over the optical fiber cable, an end of the spring pressing the ferrule; a plug housing to accommodate the ferrule assembly and the spring; and a spring cap to be connected to the plug housing for supporting another end of the spring and for curvingly leading the optical fiber cable, wherein a curved portion, provided inside the spring cap, of the optical fiber cable has a thinner cover than another portion.
As a second aspect of the present invention, in the structure with the above first aspect, the curved portion starts from a position of an end of the ferrule.
As a third aspect of the present invention, in the structure with the above second aspect, the curved portion ends near an exit opening portion of the spring cap.
According to the above-described structure of the present invention, the following advantages are provided.
(1) Because the optical fiber cable has thinner curved portions with lower rigidity the optical fiber cable can be curved easily, thereby improving the work efficiency.
(2) The spring for pushing the ferrule is arranged over the optical fiber cable securely within the set-up curved extent thereof. Because the optical fiber cable being within the set-up curved extent is thinner than that of the prior art one, the spring does not receive a pressure from the cable, which improves action of the spring, thereby reducing a force required for coupling the optical plug.
(3) The optical fiber cable is thinner than the prior art one at least within the optical plug. Therefore, because the opening portion for leading out the optical fiber cable can be narrower, thereby downsizing the optical plug.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.